In many industries, it is highly desirable to precisely dispense a very sensitive, high purity liquid in the course of manufacturing a product. For example, dispense liquids are commonly used in the microelectronics industry, such as the liquid crystal industry, the semiconductor industry, and the ink-jet printing industry, in the process of manufacturing a variety of products. An example of such a dispense liquid is a photoresist, which may be used in procedures such as photo lithography to produce an integrated circuit.
In these industries, the trend is to make parts, components, and products ever smaller. For example, circuit geometries have been reduced to the sub-micron size. At such a microscopic level, the introduction or formation of impurities in the dispense liquid is a major problem. Particulate contamination is a highly problematic impurity. Contamination of the dispense liquid with even the smallest of particles can ruin not only the dispense liquid, which can be extremely expensive, but also the products in an entire production run.
Bubbles in the dispense liquid is another problematic impurity. The formation of bubbles in the dispense liquid can be equally as devastating as particulate contamination. Dispense liquids typically include extremely volatile components, e.g., highly volatile solvents. These components can easily vaporize to form bubbles within the dispense liquid, for example, at the suction inlet of a dispense pump where the pressure can drop to a value which vaporizes the volatile components.
Another major problem associated with dispense liquids is their sensitive, fragile nature; they are easily damaged. Many processes utilize a periodic “shot” of dispense liquid rather than a continuous flow of liquid. Many conventional dispense pumps administer a “shot” by generating a high flow rate of the dispense liquid at high pressure for a short period of time. High pressures and high flow rates can adversely alter or change the properties of a dispense liquid, negatively affecting not only the dispense liquid but also the products made with the dispense liquid.